﻿ Engineering Entrance Exam Question and Answers | Thermodynamics - Zigya

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# Thermodynamics

#### Multiple Choice Questions

31.

Which of the following plots represent an exothermic reaction?

• • • • 32.

The condition for a reaction to occur spontaneously is

• $∆$H must be negative

• $∆$S must be negative

• $\left(∆\mathrm{H}-\mathrm{T}∆\mathrm{S}\right)$ must be negative

• $\left(∆\mathrm{H}+\mathrm{T}∆\mathrm{S}\right)$ must be negative

33.

For the reaction, X2Y4 (l) → 2XY2 (g) at 300 K, the values of $∆\mathrm{U}$ and $∆\mathrm{S}$ are 2 kcal and 20 cal K-1 respectively. The value of $∆\mathrm{G}$ for the reaction is

• -3400 cal

• 3400 cal

• -2800 cal

• 2000 cal

34.

The values of $∆$H and $∆$S of a certain reaction are -400 kJ mol-1 and -20 kJ mol-1K-1 respectively. The temperature below which the reaction is spontaneous, is

• 100 K

• 20$°$C

• 20 K

• 120$°$C

35.

The enthalpy of vaporisation of a certain liquid at its boiling point of 35°C is 24.64 kJ mol-1. The value of change in entropy for the process is

• 704 JK -1mol-1

• 80 JK -1mol-1

• 24.64 JK -1mol-1

• 7.04 JK-1mol-1

36.

Given that

The heat of formation of carbon monoxide will be

• y + 2x

• 2x - y

• $\frac{2\mathrm{x}-\mathrm{y}}{2}$

37.

The value of $∆$H for cooling 2 mole of an ideal monoatomic gas from 225$°$C to 125$°$C at constant pressure will be [ given Cp$\frac{5}{2}\mathrm{R}$].

• 250 R

• -500 R

• 500R

• -250 R

38.

The change of entropy (dS) is defined as

• $\frac{\mathrm{dH}}{\mathrm{T}}$

39.

For a spontaneous process, the correct statement(s) is (are)

• $\left(∆{\mathrm{U}}_{\mathrm{system}}{\right)}_{\mathrm{T},\mathrm{V}}>0$

40.

Pressure-volume (pV) work done by an ideal gaseous system at constant volume is (where E is internal energy of the system)

• -$∆$p/p

• zero

• -V$∆$p

• -$∆$E